(a) Field of the Invention
The present invention relates to an oil control valve of a vehicle engine.
(b) Description of the Related Art
Generally, an oil control valve of a vehicle engine is a component of a continuously variable valve timing (CVVT) device. The oil control valve changes a path of engine oil supplied from a hydraulic pump to the CVVT device under control of an engine control unit, and adjusts opening and closing times of an exhaust or intake valve.
Such an oil control valve includes a connector, a plunger with a permanent magnet, a coil, a spool connected to the plunger, and a sleeve. When the connector is supplied with power, a magnetic field is formed by the coil and the plunger. The plunger and spool move due to the magnetic field. A hydraulic line formed as a position between the spool and the sleeve is thus moved.
Consequently, when oil flows into an advance angle chamber or retard angle chamber of the CVVT device along such a hydraulic line, valve overlap, i.e. intake and exhaust valves being open simultaneously, is changed by such inflow of oil. Valve overlap is advantageous in common regions while it is disadvantageous in low or high speed regions. Accordingly, value overlap should be changed as described above in order to improve engine output.
However, since a conventional oil control valve is located at a cylinder head in a lower part of a cam cap, it may be directly exposed to heat radiated from a combustion chamber. Therefore, an oil control valve can be easily deteriorated. Particularly, when an oil control valve is located near an exhaust valve, deterioration speed of an oil control valve is increased because the oil control valve is directly exposed to hot exhaust gas.
In addition, since one end of the conventional oil control valve is inclined downward at a plunger, oil gathers at the plunger. Since oil gathered at the plunger may interrupt movement of the plunger, advancing or retarding responsiveness is deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.